I just linked to the first relevant info that I found - I didn't even see any SDS/MSDS there. I am actually in the USA and have worked in HDPE processing for around 25 years. If you look at an SDS for HDPE (which we go over once a year in an OSHA required meeting) you will see that it is totally inert in all states and the greatest risk of harm can come from inhaling excessive amounts of fine dust created when processing. This is a mechanical issue and not one of toxicity. The plant I've worked in for the last 15 years is actually a member of the OSHA Safety & Health Achievement Recognition Program (SHARP) and means we're audited for policy and procedure twice annually. The only safety gear we're required to wear while working all day in a plant of 10 large machines all heating HDP...

I just linked to the first relevant info that I found - I didn't even see any SDS/MSDS there. I am actually in the USA and have worked in HDPE processing for around 25 years. If you look at an SDS for HDPE (which we go over once a year in an OSHA required meeting) you will see that it is totally inert in all states and the greatest risk of harm can come from inhaling excessive amounts of fine dust created when processing. This is a mechanical issue and not one of toxicity. The plant I've worked in for the last 15 years is actually a member of the OSHA Safety & Health Achievement Recognition Program (SHARP) and means we're audited for policy and procedure twice annually. The only safety gear we're required to wear while working all day in a plant of 10 large machines all heating HDPE to around 350F are standard hearing and eye protection.As I said, though, residual chemicals from poorly washed bottles would be a separate matter.

It's 180C or 356F

Nice Instructible! Good work! I've worked in facilities that make HDPE bottles for around 25 years. I think you're more accurate with the melting point of 180C that you're using than the 120C listed in the link you provide. 120C is likely meant for LDPE. We typically use setpoints of 350F (177C), but can range in special circumstances from 330F-360F (166C-182C) If we want to lower the viscosity a lot for separating and hand-cleaning tooling we will set the heaters to 400F-450F (204C-232C). If left at these higher temperatures for very long it will start to discolor the material, though.To address some other comments here: There are not any toxic fumes produced from the melting of clean HDPE. Even when burning HDPE is relatively harmless - the smoke is no more toxic than that of wood. If...

Nice Instructible! Good work! I've worked in facilities that make HDPE bottles for around 25 years. I think you're more accurate with the melting point of 180C that you're using than the 120C listed in the link you provide. 120C is likely meant for LDPE. We typically use setpoints of 350F (177C), but can range in special circumstances from 330F-360F (166C-182C) If we want to lower the viscosity a lot for separating and hand-cleaning tooling we will set the heaters to 400F-450F (204C-232C). If left at these higher temperatures for very long it will start to discolor the material, though.To address some other comments here: There are not any toxic fumes produced from the melting of clean HDPE. Even when burning HDPE is relatively harmless - the smoke is no more toxic than that of wood. If there are chemical residues left in the bottles that would be a separate issue. Other plastics, vinyls such as PVC especially, DO release harmful fumes, however.One thought: if you would line your mold with sheet metal it may make the non-stick surface more robust. Maybe you can cut up soda cans for a lining? Alternately you could use a little metal bread pan or something from a thrift store.

While this can be a serious concern with other plastics, generally only if they are visibly burning and vinyls especially , clean HDPE does not pose any hazard. Any lingering chemicals that were contained in them are a different matter.https://www.directplastics.co.uk/whats-in-those-fumes.html

Hey thanks for the kind words! My son was obsessed with the original MIDI Fighter at the time and so was the inspiration for this. I haven't looked at expanding this particular project any as my son no longer DJs. However I am working a little here and there when I can get time on a different audio effect project. It'll maybe use an encoder but not really in any cool way.

Chargers supplying 2 amps and more are pretty common and really inexpensive now so I've just been using a cheap 2.5A. I had an antique truck that I'd made a linear supply using an LM series chip and installed into the ash tray. Soon I'll likely either be making another of those or disassembling a cheap charger and installing it directly into my dash. The cigarette plugs aren't the most stable or secure connectors and mine come loose fairly frequently.

Thank you for the kind words! It would certainly be possible to use encoders instead of pots. How that would be done is a little beyond the scope of a comment here, but the all of the variables containing "analog" and the routines that handle them would be the bits in question.